When you're feeling run-down, feverish, and achy, it might not always be the flu. Here are some other conditions that can mimic flu symptoms: **1. Common Cold:** Colds usually come on slowly and have milder symptoms like a runny or stuffy nose. **2. COVID-19:** This disease can cause fever, cough, and loss of taste or smell. **3. HIV:** Early HIV infection can cause flu-like symptoms 2-4 weeks after infection. **4. Lyme Disease:** This bacterial infection from deer ticks can cause a rash and flu-like symptoms. **5. Meningitis:** This condition inflames the coverings of the brain and spinal cord, causing fever, headache, and nausea. **6. Adenoviruses:** These can cause flu-like symptoms and other issues like pinkeye. **7. Pneumonia:** This lung infection can cause cough, fever, and trouble breathing. **8. Carbon Monoxide Poisoning:** This can cause tiredness, nausea, dizziness, and headache. If you have flu-like symptoms, it's important to see a doctor to get the right diagnosis.